In the related art, techniques are known for generating a smooth tool path by subjecting a tool path specified by instructed points to smoothing processing in a numerical control device of a machine tool. Methods based on Bezier curves, B-spline curves, NURBS curves, simple averages, and weighted averages are used as smoothing methods, for example.
However, level differences may be generated between adjacent tool paths, and machining quality may be adversely affected when smoothing processing is performed on a tool path in which there are spaces between peak feed sections in the case where curve machining such as reciprocal machining and contour machining is performed. This is caused by a characteristic of smoothing processing in that the path of an approximation curve greatly changes with small differences in line section distance between block end points of adjacent tool paths and with small differences in the shape of a tool path, such as a bent state.
PTL 1 discloses a device that sets a plurality of target points at regular intervals along a tool path read out from a machining program, and generates a new tool path by performing smoothing processing on the basis of the plurality of target points.